In the figure we have a simple thermometer with NTC, using an analog current indicator. The adjustment is made in the trimpot and the power is done by batteries.
The operational amplifier used in this application is not the most common today. The circuit is...
This basic blocking oscillator configuration was obtained from a 1954 transistor book. The...
This circuit appears elsewhere on this site, but from different sources. Using the LM3900, we find this...